Microscopic examination of a specimen to detect specimen features can be limited. Specimens as understood by a person of ordinary skill in the art refer to an article of examination (e.g., a wafer or a biological slide), and features refer to known characteristics of a specimen, as well as abnormalities and/or defects. Features can include but are not limited to: circuits, circuit board components, biological cells, tissue, defects (e.g., scratches, dust, fingerprints). In some cases, features of a specimen are distributed across relatively large surface areas, or a specimen itself is rather large. For such specimens, microscopic examination can be insufficient or undesirable, because such examination acquires information over relatively small surface areas and requires the capture of multiple images of discrete portions of a specimen in order to represent the entire specimen. In addition, microscopic examination can be limited in the type and variety of illumination it can provide. For purposes of this specification, microscopic refers to an area less than 0.5 cm2.
Accordingly, it is desirable to provide a new mechanism for macroscopic examination of a specimen that can capture the entire or large areas of a specimen in a single field of view and can provide for multiple modes of illumination including, but not limited to brightfield, darkfield or oblique illumination; polarized light; cross-polarized light; and differential interference contrast (DIC), phase contrast. It is also desirable that each mode of illumination provide variable illumination landscapes, as explained herein, to detect features of a specimen. For purposes of this specification, macroscopic refers to an area 0.5 cm2 or greater.